The present invention relates generally to a fuel vapor separator for a fuel delivery system of an internal combustion engine and, more particularly, to a fuel vapor separator that incorporates a fuel distribution network, a closed biased vent valve, and a damper chamber, among other things, to control fuel temperature and remove vapor from the fuel.
Fuel injection systems are used to supply fuel to many modem engines because their ability to precisely meter fuel flow and accurately control the mixture of fuel and air delivered to an engine, which dramatically improves engine performance while reducing engine exhaust gas emissions. In one type of fuel injection system, a fuel pump transfers fuel under high pressure directly from a fuel tank to a fuel rail connected to the individual fuel injectors of the engine. Excess fuel not used by the fuel injectors during periods of low engine demand is returned to the fuel tank. Unfortunately, the returned fuel can vaporize or become aerated and foamy when mixed with the fuel in the fuel tank, which can then lean out the air-fuel mixture delivered to the engine.
Fuel vapor separators are often used in fuel delivery systems of internal combustion engines to remove entrained vapor from the fuel. Heat build up in an engine can adversely affect the engine""s fuel delivery system by causing the fuel to become vaporized before it is introduced into the engine""s combustion chamber. The vaporized fuel interferes with proper engine combustion and, consequently, with engine power and performance. Pressure vessels, such as fuel vapor separators, are known for reducing or eliminating vaporized fuel in the fuel delivery system. The fuel vapor separator includes a housing where fuel is passed through, thereby allowing vapor to separate from the liquid fuel. During operation, the vapor is vented from the fuel vapor separator through a valve arrangement that may be operated by a float assembly.
Unfortunately, fuel that is returned to the fuel vapor separator under high pressure as well as high velocity causes the fuel to foam in the fuel vapor separator. Air and fuel vapor that is returned to the fuel vapor separator can also stir up the liquid fuel and cause the fuel to foam and vaporize. Fuel foaming is highly undesirable because it can interfere with proper cooling and maintaining enough liquid fuel in the fuel vapor separator for high pressure fuel pump operation. Should the amount of foam in the fuel vapor separator become excessive, foam may be pumped to the engine resulting in lean engine operation, stalling or, even worse, overheating of the engine due to fuel starvation. Moreover, too much fuel vapor/gas in the fuel vapor separator is also undesirable because it can result in increased fuel vapor venting from the fuel vapor separator and into the intake manifold of the engine, thereby resulting in rough engine operation, spark plug fouling, and increased exhaust gas emissions.
While these fuel vapor separators perform acceptably in many applications, they can be expensive to manufacture because of the intricacy of the component parts and the consequent long assembly time. Another disadvantage of these known fuel vapor separators is that they must be sized for use with a specific engine and thus tooling costs can be expensive in order to manufacture a variety of sizes of vapor separators for use on differing engine sizes. A further disadvantage of these fuel vapor separators is that they require extra space for a separate mechanical valve system to exhaust excess pressure from systems after the fuel vapor separator is pressurized. These fuel vapor separators are unattractive for use in certain outboard marine internal combustion engines, which are used to power boats and other watercraft.
It is advantageous for outboard marine engines to comply with United States Coast Guard safety regulations, which limits the space and the length of pressurized fuel lines connecting the high pressure fuel pump to the fuel vapor separator. Typically, to keep the length of the pressurized fuel lines as short as possible, the high pressure fuel pump, fuel vapor separator, and pressurized fuel lines are an integral part of the engine assembly and housed under its cowling.
As mentioned above, during operation of outboard marine engines, the vapor is vented from the fuel vapor separator through a valve arrangement that is operated by a float assembly. Outboard marine engines are subjected to fierce oscillations and vibrations as the boat travels over waves in the lake or sea. These unpredictable variations often cause the float in the separator to bounce up and down, leading to unintended opening of the vent valve and allowing fuel to vent into the engine, thereby temporarily flooding the engine. This condition is often referred to as xe2x80x9cengine spit.xe2x80x9d It would, therefore, be desirable to improve the design of the fuel vapor separator to overcome the aforementioned problems.
In view of the above-described potential problems relating to fuel vapor separators, the need has arisen to design a fuel vapor separator which is simple to manufacture and can be easily assembled in a variety of sizes. Such a new design of a fuel vapor separator will effectively remove vapor from pressurized fuel, distribute the pressurized fuel to all fuel injectors, and control the temperature of the pressurized fuel during engine operation.
The present invention relates to a fuel vapor separator having a fuel distribution network, a damper chamber, and a closed biased vent valve, which are assembled within the fuel vapor separator. This new design helps to minimize the limited space available within an outboard marine engine, and by its design, it is relatively simple to assemble and can be easily manufactured in a variety of sizes.
Accordingly, the present invention includes a fuel vapor separator for an internal combustion engine which includes a housing having two opposed ends. Top and bottom covers enclose the two open opposed ends of the housing and a fuel distribution network is incorporated into the fuel vapor separator to supply fuel to each fuel injector of the engine and to receive fuel return from each fuel injector.
In accordance with another aspect of the invention, a fuel vapor separator includes a housing having an enclosed chamber. A fuel float is provided that has an upwardly extending float arm located in the enclosed fuel chamber and a closed biased vent valve is mounted on the housing and controlled by the fuel float. A lever arm is connected to the closed biased vent valve, and the upwardly extending float arm such that the lever arm is configured to decouple from the vent valve to eliminate unintended opening of the vent valve.
In accordance with one further aspect of the invention, a fuel vapor separator includes a housing having two opposed ends and a top and bottom cover that enclose the two open opposed ends of the housing. The top and bottom covers are constructed substantially identical and use an interchangeable gasket disposed between the top and bottom covers and the housing. Not only is assembly and manufacturing simplified with the arrangement, but also the identical top and bottom covers, together with the interchangeable gasket, creates a plurality of coolant passage in the fuel vapor separator for coolant flow.
In accordance with another further aspect of the invention, a method is provided for reducing engine spit. The method allows float movement vertically within an enclosed fuel chamber of a fuel vapor separator without opening a vent valve that is biased in a closed position. Engine spit caused by unintended opening of the closed vent valve due to engine vibration is thereby reduced significantly and in many cases, eliminated altogether.
Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.